The present invention relates to an insulating casing or housing for thermal switches having a plastic envelope or jacket.
Insulation for thermal switches, particularly miniature bimetallic switches are known in various different constructional forms. In, for example, German utility model 73 33 932 a switch is proposed with an insulation formed from a deep-drawn plastic cap which is engaged on the switch and snugly surrounds the latter except for the connecting face, which is embedded by a casting resin. It is also proposed in DE-OS 27 28 487, inconnection with switches with a snugly surrounding insulating material cap, to pressure extrusion coat at least the free part of the switch, i.e. in particular in the vicinity of the connecting elements. Finally, it has been proposed in German Utility Model 8028913 that an envelope comprising a thermoplastic casing cup, in which the component, i.e. particularly a switch is inserted and a casing cover connected therewith by an ultrasonic weld be used.
This insulating casing fulfills the important function in connection with thermal switches of ensuring a good heat conduction from the outer area to the thermal switch, so that the latter rapidly and reliably responds to temperature changes. The known insulating casing has very thin plastic walls, so that they are unable to satisfy the protection requirements of higher protection classes. In order to satisfy these protection requirements much thicker insulating casing walls would be required, which would reduce the quality of the overall insulated thermal switch, particularly with respect to its response speed and would even make such a switch unusable.
The aim underlying the present invention essentially resides in providing an insulating casing for thermal switches which, in the case of high insulating properties, still ensures a good and rapid heat transfer from the outside to the switch located in the casing.